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6.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
Security
Security establishment procedure will be the same as in LTE
Key differences:
• Integrity protection to be supported for DRB
– Data failing Integrity protection to be discarded
• Both ciphering and integrity protection is configurable per DRB
– Certain PDU sessions may not secuirty
• Every handover may not need a key change
– Change of keys expected only if there is change in Central Unit (CU) (i.e., PDCP
location) for split CU/DU RAN
6

7.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
Mobility
Mobility procedures also similar to LTE
• No procedural changes/optimisations for Handover or inter-RAT mobility compared to LTE in
Rel-15
– Main changes are to UE measurements based on NR PHY
• Idle mode: Similar to LTE
– Priority based mechanisms of LTE re-used
– Applicable also for INACTIVE
– Changes required to support NR PHY for cell reselection measurements
7

8.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
RRM
Overall measurement framework is similar to LTE except beam related aspects.
• Three measurement types: intra-frequency, inter-frequency, inter-RAT measurements for E-
UTRA
• The association between a measurement object and a reporting configuration is created by a
measurement identity
• Reference signal: SSB for idle mode; SSB and/or CSI-RS for Connected mode
• Beam level measurement and reporting
– The UE measures multiple beams of a cell and derive the cell quality from the multiple beams
– Measurement reports may contain beam results (beam identifier only, measurement result
and beam identifier, or no beam reporting) in addition to cell quantities
• Measurement gap
– Non-gap-assisted or gap-assisted depends on the capability of the UE, the active BWP of the
UE and the current operating frequency
8

9.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
Slicing
• Network Slicing is a concept to allow Mobile Network Operators (MNO) to consider customers with
different service requirements
• Slice selection is “similar” to PLMN sharing in terms of implementation
– Dedicated frequency priorities (as in LTE) can be used by network to prioritise frequencies that
support the slices allowed
• UE can support max 8 network slices simultaneously
• Resource management between slices: Partitioning and isolation of resources
– Largely handled via implementation with no RAN standards impact
• No direct relationship in specifications between slicing and other vertical services such as
URLLC
9

10.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
Other RRC functions
System information broadcast and acquisition
• On demand SI transfer – network does not always have to broadcast SI, saves network energy and
resources
Access class barring and overload handling
• Unified Access Control mechanism different from LTE, providing similar functionality
Paging similar to LTE
• Paging occasion calculation formula updated to consider NR PHY and is S-TMSI based
Positioning
• UE operating in NR can obtain position using LTE signals and RAT independent methods
• No support for native NR methods in Rel-15 other than E-Cellid
UE capability transfer
• Similar to LTE with storage in AMF
ANR/SON (but no MDT in Rel-15)
10

11.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group

12.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
Motivation of the new RRC_INACTIVE state
Significant delay reduction in INACTIVE to CONNECTED compared to IDLE to
CONNECTED
Reduce the signalling overhead (on radio and network interfaces), enabling UE power
consumption similar to IDLE while improving the UE access latency
Key aspects:
• UE context storage in in RAN during INACTIVE
– UE context stores both 5GC information including security and UE radio configurations
– allowing transitions between INACTIVE and CONNECTED without involving Core Network
– UE centric mobility, e.g. cell (re)-selection in INACTIVE
– Transitions between Inactive and Connected, and mobility while in Inactive are hidden from CN
12

14.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
RAN-initiated paging, RAN Notification Area (RNA) and RAN
Notification Area Update (RNAU)
RRC_INACTIVE is characterized by
• Use of RAN Notification area (RNA) for
INACTIVE
– similar to CN tracking area for Idle
• RNA is configured per UE by gNB
– 1 to N cells defined by a List of cells or list of RAN
Area ID or list of TA IDs
• UE is reachable within a configured RNA
via a RAN-initiated paging
– RAN-initiated paging uses a RAN configured UE ID
(I-RNTI)
• RNAU triggered periodically and when
moving outside of the configured RNA

21.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
New QoS model for 5GC
• QoS flow based marking in Core
Network instead of EPS bearers to
differentiate QoS “streams” in a PDU
session
• RAN continue to use DRBs
– All packets in a DRB will receive
same QoS treatment
• Mapping of QoS flow to DRB is left to
gNB implementation (new concept)
– Results in two step mapping:
– IP to QoS flow in NAS
– QoS flow to DRB in AS
21

23.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
SDAP - Reflective mapping of QFI to radio
bearer
• The mapping from QFI to radio bearer is controlled by the gNB in 2 ways:
• RRC configuration signalling
• Reflective mapping
• A QFI is transmitted in the UL on the same radio bearer as that QFI was
received in DL
• Enable changing QFI to radio bearer mapping in a more dynamic way and
with lower signalling overhead
23

24.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
Packet Data Convergence Protocol (PDCP)
Header compression/decompression through the use of RoHC
Ciphering and integrity protection
• Key difference compared to LTE PDCP is that integrity protection can be
applied to user plane traffic as well as control plane signalling
Data duplication
• Key new feature compared to LTE PDCP
Duplication detection and reordering of received PDPC PDUs
24

26.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
Radio Link Control Protocol (RLC)
Similar functionality compared to LTE RLC:
• Segmentation to match the transmitted PDU size to the available radio
resources
• Error correction through ARQ
Key differences compared to LTE RLC:
• Does not provide concatenation of RLC SDUs
– Equivalent functionality now provided by the MAC layer. Motivated to enable
UL RLC PDUs to be pre processed within the UE before reception of UL
grant.
• Does not provide reordering of received RLC SDUs
– Equivalent functionality now provided by the PDCP layer
26

27.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
Medium Access Control (MAC)
• Similar functionality compared to LTE MAC:
– Multiplexing and demultiplexing of data from different radio bearers to the
transport blocks that are carried by the physical layer
– Priority handling between data from different radio bearers
– Error correction through Hybrid ARQ.
– Discontinuous reception (DRX)
• Key differences compared to LTE MAC
– Functionality to support beam based operation for high frequent operation.
– More flexible UL configured grants
– MAC PDU format optimised to enable pre-processing and facilitate low delay
27

33.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
SRB3: SCG SRB
• A new direct SRB between SeNB and UE – SRB3
– Motivation:
– Lower signalling delay over direct NR interface – no Xn delay and faster NR radio
– Less processing at MN
– Can only be used for messages that do not need coordination between MN and SN
• Can be configured based on SN decision.
– The following RRC messages can be sent via the SRB in the SCG
– RRCConnectionReconfiguration, RRCConnectionReconfigurationComplete, MeasurementReport
– SCG SRB is of higher scheduling priority than all DRBs
• UE still processes one message at a time in sequence irrespective of the path the message is received
in
33

34.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
Sub architecture options (3, 3a, 3x) and
Bearer types
Different bearer types based on:
• Bearer termination point of the CN interface; and
• Radio interface used for data transfer
Single UE may be configured with different bearer types
MN terminated and SN terminated bearer types
– Indicates where the data from core network for that bearer terminates in RAN
– Also indicates the location of SDAP (for 5GC) and PDCP entities in the network for this
bearer
– E.g., MN terminated bearer implies all the data to and from CN for this bearer is
through MN
– Does not imply anything about which radio interface is used for this bearer
34

35.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
MCG And SCG bearer
Indicates which radio interface is used to data for
this bearer
• MCG bearer implies all the data for this bearer
is sent only over MCG radio interface
– RLC bearer (RLC +MAC logical channel) in
MCG
• SCG bearer implies all the data for this bearer
is sent only over SCG radio interface
– RLC bearer in SCG
• Figure shows MN terminated MCG bearer
(option 3) and SN terminated SCG bearer
(option 3a)
35
RLC bearerRLC bearer
MN terminated
MCG bearer
PDCPLTE
RLCLTE
MACLTE
SN terminated
SCG bearer
PDCPNR
RLCNR
MACNR

36.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
MN terminated split bearer (option 3)
Split bearer:
• Indicates both MN and SN RLC bearers are configured for this bearer
• DL data can be sent over both
• UL data can be configured to be sent over
– Either one of the two UL; or
– Split over both paths; or
– Duplicated over both paths
36
MeNB (LTE)
MACLTE
SgNB (NR)
PDCPNR
RLCNR
MACNR
S1-U or NG-U
Xn
RLCLTE

39.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
Split MCG SRBs
Similar to split DRB but for MCG SRBs (SRB1 and SRB2)
• MCG signalling reliability, especially during HO
– But only relevant if there happens to be an SN at MN cell border
For DL, selection of transmission path depends on network implementation
UL packet transmission is configured by RRC to use MCG path, or duplicate on both MCG and SCG
Duplication and duplicate detection functions in PDCP
39
MeNB (LTE)
MACLTE
SgNB (NR)
PDCPNR
RLCNR
MACNR
Xn
RLCLTE
RRCMN RRCSN
Xn

40.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
Other MR-DC architectures
Other architectural options to be completed by Dec 2018 in Rel-15 late drop
• NG-EN-DC: EN-DC with 5GC
• NR-DC: NR NR Dual connectivity
• NE-DC: NR is master and LTE as secondary node
Based on EN-DC architecture
• Main differences:
– NR-DC coordination and capability handling
– Small changes Security requirements from integrity protection of DRBs
40

41.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group

42.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
Release 16 work programme (1)
3GPP will continue to evolve NR functionality in Release 16 (due for completion in
Q4 19) and beyond.
These slides provide very brief overview of the Release 16 work items led by
3GPP RAN working group 2 (working group responsibility for radio interface
protocols)
There is other work led by other working groups e.g:
• NR in unlicensed spectrum (NR-U), NR V2X, NR positioning, NR for non
terrestrial networks, etc
42

43.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
Release 16 work programme (1)
Integrated Access and Backhaul (IAB)
• Currently in a study phase
• Investigating the architecture and radio protocols impacts to introduce relaying where NR radio
interface is also used on the backhaul links to/from the relay nodes
• Motivated by the desire to enable very dense deployment for NR cells while minimising costs
associated with the backhaul network
• Aiming to support multi-hop relaying
Enhancements for Industrial IoT
• Currently in study phase
• Main focus of work is the introduction of support for Time Sensitive Networking (TSN) including
provision of accurate time reference, Ethernet header compression
43

44.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
Release 16 work programme (2)
NR mobility enhancements
• Work due to start in Q1 19
• Aiming to provide enhancements for handover interruption time and reliability
NR dual connectivity and carrier aggregation enhancements
• Work due to start in Q1 19
• Aiming to provide various enhancement to CA/DC operation including faster measurement
reporting of candidate cells and faster activation of CA and/or DC
Optimisations on UE radio capability signalling
• Currently in study phase
• Investigating mechanisms to reduce the overhead of UE capability signalling
44

45.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group

47.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group

48.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
Terminology
• NR Name of the Radio Access Technology (equivalent to E-UTRA).
• NG-RAN RAN that connects to 5GC
– Could use either the NR or E-UTRA radio access technology
– Note NG-RAN is defined by its connectivity to the 5GC and not by the radio it
uses.
• gNB Node B that used the NR Radio Access Technology
– en-gNB - Node B that uses NR for E-UTRA-NR Dual connectivity. You might
see this but not expected to be commonly used in RAN2 specs (more in RAN3
specs)
• NR, NG - are 'monolithic' terms - they do not stand for anything!
• 5G Marketing name and logo for 3GPP Rel-15 specs related to NR
– Others in the industry may use '5G' in different ways
48

49.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
Characteristics of RRC states
RRC_IDLE RRC_INACTIVE RRC_CONNECTED
UE controlled mobility based on network configuration (cell reselection)
Network controlled mobility within NR
and to/from E-UTRAN
DRX configured by NAS DRX configured by NAS or gNB DRX configured by gNB
Broadcast of system information Neighbour cell measurements
Paging (CN-initiated)
Paging (CN-initiated or
NG-RAN-initiated)
Network can transmit and/or receive
data to/from UE
UE has an CN ID that uniquely
identifies it w/in a tracking area
NG-RAN knows the RNA which the UE
belongs to
NG-RAN knows the cell which the UE
belongs to
No RRC context stored in gNB
UE and NG RAN have the UE AS context stored, and the
5GC - NG-RAN connection (both C/U-planes) is established for UE

50.
Next Generation and Standards (NGS)
Client and Internet of Things (IoT) Businesses and Systems Architecture Group
Signalling flow and use of reflective QoS in RAN and CN
50